Method and apparatus for applying small amounts of liquid substance to a web

ABSTRACT

A method and apparatus are disclosed for uniformly applying small amounts of liquid to a moving web of material. The method consists of dispersing controlled quantities of the liquid in a stream of air which is conveyed in controlled quantities to the zone of application and coalescing the liquid prior to applying it to the web. The apparatus consists of a mist generator to atomize the liquid in a stream of air, a conduit system to conduct the air stream containing the suspended droplets of the liquid to the application zone, a coalescer to convert the minute droplets of atomized liquid in the air stream to larger drops removed from their suspended state in the air stream, and an application zone where the coalesced liquid is brought into contact with the moving web of material. In the preferred use of the invention, perfume is applied to webs of tissue paper, and the method includes passing the stream of air after the perfume is precipitated from it through the tissue paper web to filter any remaining atomized perfume from the air.

[ METHOD AND APPARATUS FOR APPLYING SMALL AMOUNTS OF LIQUID SUBSTANCE TO A WEB [75] Inventor: Richard T. Ross, Aston, Pa.

[73] Assignee: Scott Paper Company, Delaware County, Pa.

[22] Filed: Jan. 27, 1972 [21] Appl. No.: 221,254

52 us. or 117/105.3, 118/300, 118/325,

[58] Field of Search 117/106, 107.1, 104,

[56] References Cited UNITED STATES PATENTS 3,690,933 9/1972 8 Cole ll7/107.l 3,677,808 7/1972 Sheridan 117/1053 Primary Examiner-Alfred L. Leavitt Assistant Examiner-Al. Massie Attorney-William J. Foley et al.

[57 ABSTRACT A method and apparatus are disclosed for uniformly applying small amounts of liquid to a moving web of material. The method consists of dispersing controlled quantities of the liquid in a stream of air which is conveyed in controlled quantities to the zone of application and coalescing the liquid prior to applying it to the web. The apparatus consists of a mist generator to atomize the liquid in a stream of air, a conduit system to conduct the air stream containing the suspended droplets of the liquid to the application zone, a coalescer to convert the minute droplets of atomized liquid in the air stream to larger drops removed from their suspended state in the air stream, and an application zone where the coalesced liquid is brought into contact with the moving web of material. In the preferred use of the invention, perfume is applied to webs of tissue paper, and the method includes passing the stream of air after the perfume is precipitated from it through the tissue paper web to filter any remaining atomized perfume from the air.

7 Claims, 4 Drawing figures PATENTED DEE 41975 sum 1 BF 2 PATENTEDDEC 4mm BLT/SL763 suwznr 2 1 METHOD AND APPARATUS FOR APPLYING SMALL AMOUNTS F LIQUID SUBSTANCE TO A WEB BACKGROUND OF THE INVENTION fume to the tissues has presented a problem because the amount of perfume applied to the tissues must be quite small, often as small as 0.1 milligram of perfume per facial tissue. Application of large quantities must be avoided not only because of excessive cost added to an already very competitively priced product, but also because of the undesirability of an overly strong scent. Perfume application is further complicated by the unpleasant strong odor of the concentrated perfume to men working in the vicinity of the application equipment.

One method which has been used to apply perfume to tissue paper is spraying. At least two disadvantages are inherent in the spraying method. First, spraying fouls the air in the vicinity of the application equipment with perfume odors and creates an unpleasant working environment. Second, the spray head requires the use of small orifices which are subject to plugging with trash.

This plugging problem is inherent in many prior art application methods which use equipment having small passageways (for example, 0.005 inch in diameter) for metering the small quantities of perfume to the application zones. On the other hand, the use of large passageways in the equipment of the prior art would not allow the degree of uniform quantity flow control needed to produce a quality product.

Another method which has been used to apply perfume to tissue paper uses a moving mechanical member to wipe the perfume onto the tissue paper. In addition to the metering problems which are present, this type of system requires complicated drive systems and is especially undesirable where the perfume is to be applied at many locations, as is commonly the case where perfume is applied to multiple webs of tissue at the same time.

Therefore, with the shortcomings of the prior art in view, it is an object of the invention to apply perfume to porous webs such as tissue paper with precision control of the flow rate of perfume. It is also an object of the invention to apply perfume to porous webs such as tissue paper in a manner which does not allow an unpleasant quantity of the perfume to escape into the air in the working area surrounding the application equipment. A further object of the invention is to apply perfume to porous webs such as tissue paper with equip ment not requiring small orifices which are subject to plugging. And yet another object of the invention is to apply perfume to porous webs such as tissue paper with equipment inexpensively adaptable to applying the perfume at numerous locations at the same time.

SUMMARY OF THE INVENTION These and other objects are accomplished by dispersing the liquid perfume in a moving stream of air which carries the perfume to the application zones, coalescing the minute droplets of atomized perfume to form larger drops of perfume unsuspended in the air stream, and then contacting the coalesced perfume with the tissue paper. In the preferred method of the invention, the air stream is passed through the web of tissue paper to filter any atomized perfume which might remain suspended in the air. The method combines the advantage of flowing a comparatively large volume of fluid with the advantage of applying the perfume to the web in a coalesced form. The ratio of perfume to air can be regulated, and therefore, the flow volume of air which is desirable for good fluid flow control and which enables use of large passageways can be maintained independently of the small flow quantity of perfume.

An example of flow volumes which have been found satisfactory for practicing the invention is approximately one cubic foot of air flowing to each application zone per minute, conveying approximately 0.2 cubic centimeters of perfume per minute. At these flow rates, the ratio of airflow to perfume flow is approximately 140,000 to 1. This example is not given to indicate the satisfactory flow volume range of the appratus, but rather to illustrate the very small amount of perfume which can be flowed through the appratus with the flow control advantages of larger quantities of flowing fluids.

The appratus of the invention consists of means for supplying a stream of air, a mist generator for atomizing the liquid perfume in the stream of air, a manifold system for conducting the stream of air carrying the suspended perfume droplets to the vicinity of the application zones, branch conduits to conduct a uniform portion of the fluid to each individual application zone, coalescers to convert the minute droplets of perfume to larger drops removed from their suspended state in the air stream prior to applying the perfume to the porous web, and application zones where the tissue paper is brought into contact with the perfume. The apparatus is capable of uniformly conveying small quantities of perfume without the use of very small passageways. The flow volume of the air is sufficient to enable use of relatively large passageways, no smaller in size than on the order of one thirty-second inch in diameter, throughout the conduit system and in the mist generator. The unlikeliness of plugging passageways is further enhanced by the arrangement of the smallest passageways in plurality side by side, offering alternate routes in the event one becomes plugged, and by locating the smallest passageways in the apparatus remote from the dust and fibers of the moving paper webs.

BRIEF DESCRIPTION 0F THE DRAWINGS FIG. 1 illustrates the apparatus of the invention in position to apply perfume to tissue paper at convenient locations on a tissue paper folding apparatus;

FIG. 2 is an enlarged view of the application zone shown in FIG. l, and with the tissue paper removed in order to show the details more clearly;

FIG. 3 is a side view of the application zone as viewed from line 33 of FIG. 2; and

FIG. 4 is a sectional view of the branch conduit leading to the application zone as viewed along line 44 of FIG. 2.

Description of the Preferred Embodiment The preferred form of the invention is illustrated in FIG. 1, where the apparatus applies perfume to tissue paper at fold pans of a tissue paper folding apparatus. The tissue paper folding apparatus, of which a portion is illustrated in FIG. 1, is of the type described in U.S. Pat. No. 3,199,861. The folding apparatus forms no part of the invention except to illustrate a convenient location to apply the perfume to the tissue paper. Therefore, it shall be described only to the extent necessary for appreciation of the chosen locations of the perfume application zones.

The tissue paper folding apparatus generally consists of a stand 6 supporting parent rolls 7 of tissue paper and a folding and assembling region through which the webs 8 of tissue paper are passed. In the folding and assembling region the webs 8 are processed through the preliminary folding device 9, the preliminary interfolding device 10, and the final interfolding device 11, before being stacked upon the moving conveyor 12. The preliminary interfolding device 10 has been found to be a satisfactory and convenient location for applying the perfume to the tissue paper web 8. A typical folding apparatus for forming a stack of 100 sheets of folded tissues employs 50 interfolding devices 10. The perfume is preferably applied at all of the interfolding devices 10.

The apparatus of the invention is illustrated in FIG. I as mist generator 13, manifold 14, branch conduits 15, and perfume application zones 16. The mist generator 13 atomizes liquid perfume in a stream of moving air. The mist generator can be provided by a commercially available device for atomizing liuqids in an air stream. One such commercially available mist generator which has been found satisfactory for use in the invention is available from Alemite Division of Stewart- Warner Corporation as Oil Mist Generator Series Model 3722. The mist generator 13 requires a steady supply of air under pressure to function. The pressurized air can be supplied by any form of air compressor well-known in the art. The pressure and volume of air entering the mist generator 13 is regulated by a valve in the mist generator unit.

The manifold 14 conducts the stream of air containing the suspended atomized perfume to the vicinity of the divers application zones 16 throughout the tissue paper folding machine. In the vicinity of each application zone 16, a branch conduit conducts a portion of the air and atomized perfume to the application zone 16.

FIGS. 2 and 3 illustrate a typical application zone 16, where branch conduit 15 conducts the fluid into distribution tubes feeder 17 located adjacent tissue paper guide plate 18. From the distribution tubes feeder 17, the fluid passes through distribution tubes 19 to the surface of the tissue paper guide plate 18 where the fluid contacts the tissue paper. It should be noted here that the illustration of two distribution tubes 19 in FIG. 3 is not intended to limit the number which can be used, but it is desirable to contact the tissue paper at several places across the paper web width. Toward that desired end, the distribution tubes 19 have multiple channels in them leading to the tissue paper guide plate 18.

A coalescer 20 is located in each branch conduit 15 just before connection to the distribution tube feeder 17. The coalescer 20 removes the atomized perfume from its suspended state in the air stream by exposing the fluid stream of air and atomized perfume to a large amount of surface area upon which the small droplets of atomized perfume can adhere and precipitate from the air stream. The preferred form of coalescer 20, illustrated in FIG. 4, is a bundle of very small tubes 21 (preferably within the range of one thirty-second to one-sixteenth inch I.D.) packed together in the passageway of branch conduit 15. However, coalescers having forms other than a bundle of small tubes could be substituted for the preferred form. For example, a coalescer employing a maze of passageways which also causes the air stream to contact a large surface area would work satisfactorily.

As larger amounts of the atomized perfume collect on the walls of the coalescer tubes 21, the small droplets coalesce to form large drops of perfume. The coalesced drops of perfume collected on the walls of the coalescer 20 are dragged by the air stream through the distribution tubes feeder l7 and the distribution tubes 19 to the surface of the tissue paper guide plate 18, where the web 8 of tissue paper absorbs the perfume.

The tissue paper guide plate 18 was chosen as the location for applying the perfume to the tissue paper because it is a convenient location for that purpose located on existing equipment. Other surfaces to which the distribution tubes 19 can be attached and which tissue paper can be passed over without injuring the paper could also have been chosen.

After leaving the confines of the conduit system leading from the mist generator 13 to the tissue paper guide plate 18, the air stream no longer drags the coalesced droplets of perfume with it. Thus, the perfume is left upon the surface of the guide plate 18 where it is absorbed by the web 8 of tissue paper passing over the guide plate 18. Uniform perfume application requires the web 8 to continuously absorb the perfume as the perfume arrives at the application surface. This requirement is satisfied by maintaining the moving web 8 firmly against the application surface, thus preventing any excess accumulation of perfume on the application surface. The tissue paper guide plate 18 is well-suited for accomplishing this goal because the curved surface of the guide plate 18 in bending the moving web 8 sliding over the guide plate 18 causes the web 8 to press firmly against the guide plate 18. Also in accomplishing the goal of uniform perfume application, it is preferable that the distribution tubes 19 enter the guide plate 18 at its curved surface.

In the preferred embodiment of the invention, the air stream after leaving the distribution tubes 19 passes through the porous web 8 of the tissue paper. Passing the air stream through the tissue paper accomplishes at least two beneficial results. First, it allows the tissue paper web 8 to be passed snugly over the surface of the guide plate 18 to form a seal with the conduit system for preventing the perfume from escaping to the air. Second, it enables the tissue paper web 8 to filter out any droplets of perfume still suspended in the air stream, thus preventing perfume losses and fouling of the working environment with an odor which is unpleasant in concentrated form.

In determining the sizes of the apparatus components of the invention, general principles of fluid flow mechanics well-known to those skilled in the art are followed. Several considerations peculiar to this particular application must be kept in mind. First, it is desirable to have all passageways in the conduit system large to prevent clogging. Second, it is desirable to use a mist-generator 13 which produces an air stream and atomized perfume flow having a large ratio of air to perfume to enable precision control of perfume flow. Third, the manifold 114 size should be large enough to cause pressure drop in the fluid stream negligible compared to the pressure drop of the fluid in each branch 15, so that uniformly equal amounts of perfume will flow to each application zone 16. Fourth, the air volume capacity of the mist-generator 13 should be large in order to allow accurate control of the fluid flow. Fifth, the air volume flow to each application zone 16 must be small enough to prevent damaging the tissue paper web 8 when the air flows through it.

The method and apparatus of the invention has been described for its preferred use of applying perfume to tissue paper. But it is to be recognized that the invention can be used advantageously to apply other liquids in small amounts to tissue paper or other porous webs. The invention could also be used to apply liquid in small amounts to non-porous webs, although such a use would require diverting the air stream away from the web after conveying the perfume to the application zone. However, in the case of applying perfume to porous webs, it is preferable to pass the air stream through the web for the advantages already stated. It is also to be recognized that gases other than air could be used to convey the atomized liquid, air being chosen as the preferred gas primarily because of its inexpensiveness.

What is claimed is:

1. Method of uniformly applying small amounts of liquid substance to a moving web, comprising the steps of:

establishing a stream of gaseous carrier material flowing to the moving web at a predetermined flow rate;

dispersing the liquid substance in the stream upstream of the web at a predetermined small ratio of liquid substance to carrier material;

transporting the dispersed liquid substance in the stream to the moving web;

passing the stream through means for removing the liquid substance from its dispersed state, whereby liquid substance is removed from its dispersed state in the stream before the liquid substance contacts the moving web; and

contacting the moving web with the undispersed liquid substance.

2. Method of uniformly applying small amounts of liquid substance to a moving porous web, comprising the steps of:

establishing a stream of gaseous carrier material flowing through the porous web at a predetermined flow rate;

dispersing the liquid substance in the flowing stream of gaseous carrier material upstream of the porous web at a predetermined small ratio of liquid substance to carrier material;

flowing the carrier material before it flows through the porous web through means for separating the liquid substance from its suspended state in the carrier material, whereby liquid substance is separated from its suspended state in the carrier material before the carrier material flows through the porous web; and

absorbing the separated liquid substance into the porous web.

3. Method of uniformly applying small amounts of perfume to a moving web of tissue paper, comprising the steps of:

establishing a stream of air flowing through the tissue paper at a predetermined flow rate; and

atomizing the perfume into a mist suspended in the flowing stream of air at a predetermined small ratio of liquid substance to carrier material;

flowing the stream of air and perfume mist through a plurality of small passageways before the air stream is flowed through the tissue paper to coalesce perfume mist on the walls of the passageways;

transporting the coalesced perfume to the porous web by dragging the coalesced perfume with the flowing air stream; and

absorbing the coalesced perfume into the porous web.

4. Apparatus for uniformly applying small amounts of liquid substance to a moving porous web, comprising: means for establishing a stream of gaseous carrier material flowing through the porous web;

means for dispersing the liquid substance in the stream of gaseous carrier material upstream of the porous web;

means for separating a substantial portion of the liquid substance from its suspended state in the carrier material before the carrier ma"terial flows through the porous web;

means for contacting the separated liquid substance with the porous web, whereby it is absorbed by the porous web.

5. Apparatus for uniformly and controllably applying small amounts of perfume to a moving web oftissue paper, comprising:

an application surface upon which the web of tissue paper is in moving contact;

means for establishing a moving stream of air;

a mist generator for atomizing the perfume in the moving stream of air at a predetermined ratio of perfume to air;

means for controlling the flow rate of the stream of air containing the atomized perfume, whereby the flow rate of the perfume is controlled;

conduit means for conducting the stream of air from the mist generator to the application surface; and

a coalescer in the conduit means near the application surface to coalesce the perfume from the stream of air prior to being applied to the web of tissue paper.

6. Apparatus according to claim 5, wherein the application surface is adaptable for forming a seal with the web of tissue paper moving over the surface and with the conduit means, whereby the perfume is substantially prevented from escaping to the atmosphere.

7. Apparatus according to claim 6, wherein the coalescer is provided by a bundle of small tubes in the con- 

2. Method of uniformly applying small amounts of liquid substance to a moving porous web, comprising the steps of: establishing a stream of gaseous carrier material flowing through the porous web at a predetermined flow rate; dispersing the liquid substance in the flowing stream of gaseous carrier material upstream of the porous web at a predetermined small ratio of liquid substance to carrier material; flowing the carrier material before it flows through the porous web through means for separating the liquid substance from its suspended state in the carrier material, whereby liquid substance is separated from its suspended state in the carrier material before the carrier material flows through the porous web; and absorbing the separated liquid substance into the porous web.
 3. Method of uniformly applying small amounts of perfume to a moving web of tissue paper, comprising the steps of: establishing a stream of air flowing through the tissue paper at a predetermined flow rate; and atomizing the perfume into a mist suspended in the flowing stream of air at a predetermined small ratio of liquid substance to carrier material; flowing the stream of air and perfume mist through a plurality of small passageways before the air stream is flowed through the tissue paper to coalesce perfume mist on the walls of the passageways; transporting the coalesced perfume to the porous web by dragging the coalesced perfume with the flowing air stream; and absorbing the coalesced perfume into the porous web.
 4. Apparatus for uniformly applying small amounts of liquid substance to a moving porous web, comprising: means for establishing a stream of gaseous carrier material flowing through the porous web; means for dispersing the liquid substance in the stream of gaseous carrier material upstream of the porous web; means for separating a substantial portion of the liquid substance from its suspended state in the carrier material before the carrier material flows through the porous web; means for contacting the separated liquid substance with the porous web, whereby it is absorbed by the porous web.
 5. Apparatus for uniformly and controllably applying small amounts of perfume to a moving web of tissue paper, comprising: an application surface upon which the web of tissue paper is in moving contact; means for establishing a moving stream of air; a mist generator for atomizing the perfume in the moving stream of air at a predetermined ratio of perfume to air; means for controlling the flow rate of the stream of air containing the atomized perfume, whereby the flow rate of the perfume is controlled; conduit means for conducting the stream of air from the mist generator to the application surface; and a coalescer in the conduit means near the application surface to coalesce the perfume from the stream of air prior to being applied to the web of tissue paper.
 6. Apparatus according to claim 5, wherein the application surface is adaptable for forming a seal with the web of tissue paper moving over the surface and with the conduit means, whereby the perfume is substantially prevented from escaping to the atmosphere.
 7. Apparatus according to claim 6, wherein the coalescer is provided by a bundle of small tubes in the conduit means. 